Police continued to comb Paris on Tuesday in the search for a gunman who spread terror across the French capital.

Detectives issued a new picture of the suspect – in his 40s, stocky and with close-cut greying hair – and were searching their records after reportedly finding DNA samples in the car he hijacked.

Emmanuel Quemener of the police union Alliance said a special unit had been set up to deal with reports of sightings of the man, who shot and critically injured a photographers' assistant at the newspaper Libération.

The victim, 23, who suffered wounds to the back, chest and abdomen, was said to have regained consciousness in hospital on Tuesday but remained in intensive care.

A driver taken hostage and ordered to drive to the Champs-Élysées on Monday said the gunman threatened to blow up his car with a grenade if he refused.

"When he took the motorist hostage yesterday afternoon, the suspect said he'd just come out of prison. If that's true, it means he is on the records and that will help speed up the process of identifying him. But we have to remain cautious about this element especially as it won't necessarily help us find him," Quemener added.

Police have received more than 2,000 tip-offs from members of the public claiming to have recognised or spotted the gunman, who also threatened an editor at the television channel BFM TV on Friday, and fired a shot at a Société Générale bank at La Défense on Monday.